That is not about the "resistance" but the need. Most arduino users do not work for LHC or NASA and their designs work just fine with a superloop
pito,
Given a choice of a supperloop or two simple tasks, scientists who write device code choose the simpler more reliable task model. A RTOS provides better partitioning of an application even in simple cases.
Old EEs make the funny spaghetti supperloop that mixes timing and code for two distinct operations.
I think experimental physics groups adopt things like RTOSs more readily because the learning overhead is shared. Members help each other, the first person to learn the system helps the next person.
A RTOS is not like learning a new programming language. It requires a different architecture for embedded systems. That's why modern embedded systems text books don't emphasize details of the OS. These books cover things like why preemption is required for rate monotonic scheduling and why this is important for reliable systems.